Christian theology, with very few exceptions, has recently been rather dismissive of the ontological proof, or has suggested that it should not be regarded as a proof of the existence of God at all. Yet the argument has been held in high esteem during Western intellectual history; philosophers have for the most part treated it with respect since its revival in the second half of the twentieth century. This essay takes a fresh look at four prominent versions of the ontological proof: Anselm’s Proslogion arguments, the argument put forward by Descartes, and the modal argument of Leibniz defended by Hartshorne and, with reservations, by Plantinga. Did Anselm intend to prove the existence of God, and how do his arguments relate to their modern counterparts? The core of this essay is an examination, with an eye on contemporary theology, of the most frequently raised objections against non-modal and modal ontological arguments. While none of these objections appears to be successful, the most promising one, perhaps, is to deny the logical possibility of a most perfect being altogether. The upshot, however, is that the prospects for a refutation of either the non-modal or the modal ontological argument are much less bright than prevailing sentiment in theology has it.